Taking beta cells from the donor pancreas and transferring them to a person with diabetes is called islet cell transplantation. beta cells are the type of cells in the pancreas that produce insulin, which has a role in regulating blood glucose levels. After transplantation, the donor cells begin to make and release insulin.
Benefits of islet cell transplantation
Successful islet cell transplantation can significantly improve the quality of life for people with diabetes.
After transplantation, islet cells regain their insulin-releasing function and can maintain normal blood glucose levels in response to food, exercise, and other changes in the body.
Successful islet cell transplantation can provide the following benefits.
- Restore or improve the body’s ability to regulate blood glucose levels, eliminating the need for frequent blood glucose checks or daily insulin injections. For a small percentage of patients, none of these needs are present for 3 years after islet cell transplantation. Although insulin injections may not be needed for only a few months to a year, islet cell transplantation may reduce the risk of hypoglycemic episodes in the long term.
- Increased quality of life.
- Slows the progression of long-term complications of diabetes such as heart disease, kidney disease, stroke, and nerve and eye damage.
Risks of islet cell transplantation
As with all organ and tissue transplants, rejection of donor cells by the recipient is the biggest challenge. The role of the immune system is to protect the body from “foreign” substances, such as bacteria and viruses. Although the transplanted islet cells are beneficial, the recipient’s immune system may recognize them as “foreign” and try to destroy them, an attack on the donor tissue called “rejection.
All transplant recipients must take strong medications for life to suppress the immune response and prevent rejection. Many of these drugs have serious side effects. The long-term effects of immunosuppressive or anti-rejection drugs are not known, but they may increase the risk of cancer.
Success of transplanting islet cells for diabetes
Scientists developed transplanted islet cells to treat diabetes in the 1960s. The first transplant attempts from the 1990s had only an 8% success rate, which may be attributed to the anti-rejection drugs used at the time that interfered with the effectiveness of insulin.
But in 1999, a clinical trial at the University of Alberta in Edmonton, Canada, offered new hope. Using enhanced techniques to collect and prepare extremely fragile donor islet cells and using modified anti-rejection drugs, researchers achieved a 100% success rate, and all patients in the trial were insulin-free for at least 1 month.
However, the success of what has been called the “Edmonton protocol” has not been replicated successfully in subsequent trials, and the number of islet cell transplant procedures has declined in recent years. The Collaborative Islet Transplant Registry reported in 2009 that the proportion of adults with type 1 diabetes who did not need insulin injections at one year, 50% at 2 years, and 35% at 3 years for those who underwent surgery was 70%.
Can all people with diabetes receive islet cell transplantation?
Usually, candidates for islet cell transplantation are between 18 and 65 years of age, have had type 1 diabetes for more than 5 years, and have diabetes-related complications, such as frequent loss of consciousness due to lack of insulin and early signs of kidney disease that may lead to renal failure.
As with all medical procedures, the risks and benefits of islet cell transplantation must be carefully weighed. Transplantation is indicated for patients with comorbid severe diabetic complications.
Can islet cell transplantation be performed in all hospitals?
The procedure is still considered an experimental therapy, so islet cell transplantation for diabetes is not widely used. There are 17 centers in the United States participating in islet cell research programs. The American Diabetes Association (ADA) recommends that pancreatic or islet cell transplantation be performed only at certain major centers that are best suited to handle the complex, long-term medical and personal needs of transplant patients.
Looking ahead for islet cell transplantation research
The current focus of islet cell transplantation research is on two main areas.
- Obtaining sufficient islet cells for transplantation: obtaining sufficient islet cells for transplantation is a major challenge. In most cases, transplantation requires islet cells from several different donors. Because the need exceeds the number of human donors, researchers are studying the use of cells from other sources, including embryonic tissue and animals (such as pigs). Researchers are also trying to grow human islet cells in the laboratory.
- Preventing rejection: Researchers continue to develop new and better anti-rejection drugs. Over the past 15 years, there have been many advances in anti-rejection drugs. Newer drugs (such as tacrolimus and rapamycin) are having fewer side effects than older drugs (cyclosporine and prednisone, for example).
Researchers have also worked to develop ways to transplant islet cells to reduce or eliminate the risk of rejection and the need for immunosuppression. One approach involves coating islet cells with a special gel that prevents the immune system from recognizing and targeting the donor cells.